With the improvement and expansion of backbone infrastructure in recent years, the focus of attention in the optical communication market is being directed to the furnishing of user line equipment and equipment for connecting user lines with the backbone. Specifically, enhancement of metro area networks, access systems, and school and company LANs and higher speeds and greater capacities in provider's servers and routers are being desired.
In particular, optical connections in a school or company LAN or among servers, routers, etc., within a provider are called VSR (Very Short Reach) or interconnections. Although being short in distance, signal transmissions of high speed and high volume are desired of such optical connections. Since low cost is also desired, expensive equipment, such as that required for optical connection at a transmission rate of 10 Gbps, is not suitable even if it enables high speed.
Due to such demands, optical modules for performing parallel transmission of optical signals at a maximum rate of approximately 2.5 Gbps are being noted. With such an optical module, a tape fiber, which is an optical fiber array, and an optical semiconductor element array are aligned and connected to transmit a plurality of optical signals in parallel. However, if the alignment is performed by fiber alignment, a low-cost optical module cannot be realized. Optical modules, with which alignment is carried out by passive alignment, have thus been proposed (Japanese Patent Application Laid-Open No. H7-77634, Japanese Patent Application Laid-Open No. H7-151940).
FIG. 7 is a sectional view showing an arrangement example of a conventional passive alignment type optical module (see the document, “IEICE Technical Report LQE99–130, pp. 1–6”). The alignment of an optical fiber 92 and an optical semiconductor element 94 is carried out by the insertion and adhesion of guide pins 95, provided in a fiber ferrule 91, into guide pin insertion holes 96 provided in a substrate 93. Here, the optical fiber 92 is inserted in a fiber insertion portion that is aligned with respect to the guide pins 95 and optical semiconductor element 94 is aligned and fixed on the substrate 93 using an aligning mark, formed by the same mask process as the guide pin insertion holes 96, as a guide.